3 The Input Hypothesis Model
The next three chapters look at the ways in which more general theories of
second language acquisition have drawn on the type of syntactic evidence
and the view of sequence of acquisition discussed in the previous chapter.
This chapter is concemed with the Input Hypothesis proposed by Stephen
Krashen. During the late 1970s Krashen put forward an account of SLA
first known as the Monitor Model after its main claim about the role of
monitoring in language leaming (Krashen, 1979). In the early 1980s tbis
was expanded into a broader-based model, described in Krashen (1981;
1982). The aspect of the model that became most developed was termed
the Input Hypothesis , the title of Krashen's last major theoretical book
(Krashen, 1985a) and the name by which the model will be known here.
From the beginning, Krashen's ideas have been the subject of controversy.
The discussion here does not folIowall their ramifications but concentrates
on the Input Hypothesis as put forward in Krashen (1985a), working back
where necessary to earlier formulations. Initially the model will be presented as far as possible through the evidence and claims that he makes
bimself.
3.1 THE FIVE HYPOTHESES
The theory consists of five linked 'hypotheses': input, acquisition/leaming,
monitor, natural order, and affective filter; these are summarised on p.55
below. The Input Hypothesis is simply stated: 'humans acquire language in
only one way - by understanding messages or by receiving "comprehensible input" , (Krashen, 1985a, p. 2). That is to say, language acquisition
depends upon trying to comprehend what other people are saying.
Provided that the leamer hears meaningful speech and endeavours to
understand it, acquisition will occur. L2 acquisition fails to occur when the
leamer is deprived of meaningfullanguage, say by classroom activities that
concentrate on the forms of language rather than on meaning, or by a
psychological block that prevents otherwise useful language from gaining
access to the leamer's mind.
Listening is the crucial activity. L2 leamers acquire a new language by
hearing it in contexts where the meaning of sentences is made plain to
them. Speaking is either unnecessary or is positively harmful; active knowledge of how to use an L2 never comes from production; its only positive
virtue may be that it provokes other people into speaking themselves, thus
providing more listening material for the leamer to work on. 'Speaking is a
51
52
The Input Hypothesis Model
result of acquisition and not its cause' (Krashen, 1985a, p. 2). This emphasis on listening at the expense of production distinguishes Krashen's theory
from most others, for instance from 'communicative' teaching theories,
which stress the importance of the leamer speaking.
Various qualifications have to be made to this broad claim. Krashen
distinguishes knowledge that is acquired from knowledge that is leamt 'the AcquisitionlLearning Hypothesis' . The process of L2 'acquisition' uses
the language faculty in essentially the same unconscious way as first
language acquisition; it leads to the ability to actually use the L2. In the
process of language 'leaming', however, knowledge is gained through
conscious understanding of the roles of language. Hence 'leaming' occurs
in the second language, but is extremely rare in the first; it is furthermore
only available to L2 leamers who are capable of understanding roles, say
those above a certain age. Krashen accepts that other things than comprehensible input can lead to language knowledge of a kind; but he denies that
the form such knowledge takes is capable of being the basis for normal use
of language. If you leam the set of English pronouns by heart or you
consciously understand the various meanings of English tenses, you indeed
know something about English. But this 'leamt' knowledge cannot be used
to express something that you actually want to say.
'Leamt' knowledge comes into play through the 'Monitoring' of speech;
Monitoring provides a conscious check on what the speaker is saying.
Anything the leamer wants to say comes from acquired knowledge; leamt
knowledge can Monitor this speech production before or after actual
output. Leamers who use their acquired knowledge to say "He is going"
can check against their leamt knowledge whether "he" is the appropriate
pronoun, whether the present continuous is the appropriate tense, whether
"is" should agree with "he", and so on. Monitoring uses leamt knowledge
as a quality check on speech originating from acquired knowledge. It takes
place 'before we speak or write or after [self-correction]' (Krashen, 1982,
p. 15). The 'Monitor Hypothesis' claims that consciously 'leamt' knowledge is only available for Monitoring rather than usable in other ways. The
following diagram encapsulates the crocial relationships:
Leamt
knowledge
I
(Monitoring)
Acquired knowledge
1
--------~)
1
Output
The Monitor Model 0/ L2 production (adapted from Krashen, 1981, p. 7)
The Five Hypotheses
53
The extent to which a given learner uses Monitoring depends on several
factors: tasks that focus on 'form' rather than meaning, such as 'fill-in-theblank' tasks, will encourage Monitoring; the personality of learners varies
between those who under-use Monitoring, over-use Monitoring, or use
Monitoring optimally. Note that 'Monitoring' with a capital letter is distinct from 'monitoring' with a small 'm' found in first language use, because
it employs consciously known and verbalisable rules rather than 'feel' for
language. It is important to realise Krashen's firm belief that 'learnt'
knowledge can never be converted into 'acquired' knowledge; learning a
rule for the past tense consciously never allows one to develop an unconscious ability to use the past tense in speech; Krashen's theory 'is a "no
interface" position with respect to the relationship between acquisition and
learning' (Krashen, 1985a, p. 38).
To be useful to the learner, the input must be neither too difficult to
understand nor too easy. This is conceptualised by Krashen in terms of the
learner's current level, called i, and the level that the learner will get to
next, called i + 1. For the learner to progress rather than remain static, the
input has always to be slightly beyond the level at which he or she is
completely at horne; the gap between the learner's i and the i + 1 that he or
she needs is bridged by information drawn from the situation and from the
learner's previous experience. 'We also use context, our knowledge of the
world, our extra-linguistic competence to help us understand' (Krashen,
1982, p. 21). Comprehensible input relies on the actual language forms
being incomprehensible, not the total message. This concept has indeed
been called 'incomprehensible input' because the learners always have to
struggle to derive meaning for the parts they do not understand rather than
understanding the sentence completely (White, 1987). The learners progress continually from stage i to stage i + 1 along apre-set series of stages.
So the model requires a precise developmental scale on which i and i + 1
can be located. This scale invokes the natural order hypothesis: 'we acquire
the rules of language in a predictable order, some rules tending to come
early and some late' (Krashen, 1985a, p. 1). The developmental scale is
made up of 'rules' treated as discrete items learnt in sequence. It is largely
based on the sequences of acquisition which were discussed in the previous
chapter.
But it is still necessary to explain why acquisition is not equally successful
for all L2 learners, even when they receive apparently identical comprehensible input; 'comprehension is a necessary condition for language acquisition but it is not sufficient' (Krashen, 1982, p. 66): something more than
comprehensible input is needed. For acquisition to take place, the learner
has to be able to absorb the appropriate parts of the input. There can be 'a
mental block that prevents acquirers from fully utilizing the comprehensible input they receive for language acquisition' (Krashen, 1985, p. 3).
This block, called 'the affective filter', might be because 'the acquirer is
54
The Input Hypothesis Model
unmotivated, lacking in self-confidence, or anxious' (Krashen, 1985a, p.
3). The Affective Filter Hypothesis ascribes variation between learners to
their psychological states. If the filter is 'up', comprehensible input cannot
get through; if it is 'down', they can make effective use of it. In particular
the reason why younger learners are better at L2 acquisition over the long
term is that 'the affective filter gains dramatically in strength at around
puberty' (Krashen, 1985a, p. 13). Older learners are cut off from proper
access to comprehensible input by the increased strength of the filter.
The following diagram captures these relationships. It is adapted from
Gregg (1984), who combines Krashen's diagrams of production and acquisition into one:
Learnt knowledge
Affective
filter
I
I
I
I
(Monitoring)
1 1
Comprehensible:
r::"L-------,
•
I
anguage
mput
~ I ~ A
. ·t·
~ Acquired ~ Output
cqUlsllon
Device (LAD)
knowledge
The Input Hypothesis Model o[ L2 learning and production (adapted
from Krashen, 1982, pp. 16 and 32; and Gregg, 1984)
In Krashen's words, 'comprehensible input and the strength of the filter are
the true causes of second language acquisition' (Krashen, 1982, p. 33), one
positively, one negatively.
The Language Acquisition Device (LAD) seen in Chapter 1 features
prominently in the model, though it is seldom discussed in detail. To
Krashen, the LAD is made up of the naturallanguage learning abilities of
the human mind, totally available in LI acquisition, available in L2 acquisition according to the level of the filter; this construct is called the
'organiser' in Dulay et al. (1982). Language input comes into the mind;
LAD processes it and produces an internal grammar of the language. This
seems equivalent to the black-box LAD from Chomsky (1964), as Krashen
(1981, p. 110) suggests, though without the evaluation measure. Krashen
(1985a, p. 25) updates this to the later Chomskyan image of 'the mental
organ devoted to language'. During 'acquisition' the innate mental structures of LAD treat the input in various predetermined ways to derive
knowledge of language. The process of 'learning', unlike the process of
'acquisition', uses 'faculties of mind outside the LAD' (Krashen, 1985b,
p.30).
On the other hand the first language does not bulk large in the model,
Krashen's Evidence for the Input Hypothesis
55
either in production or leaming. Krashen allocates to the LI the fall-back
role suggested by Newmark and Reibel (1968). Transfer from LI to L2 is
due to ignorance rather than to the inevitable transfer of habits: L2
leamers often want to say more in the L2 than they can express, because of
their low knowledge of the L2. The gap between their intentions and their
speech is filled by mIes borrowed from the LI; 'the LI may "substitute" for
the acquired L2 as an utterance initiator when the performer has to
produce in the target language but has not acquired enough of the L2 to do
this' (Krashen, 1981, p. 67). The causes of such transfer are that the leamer
has been forced to speak too soon, contrary to the initial need for the
leamer to be silent, or has been asked to perform an inappropriate task
such as translation (Dulay et al., 1982, p. 119).
The Input Hypothesis: 'humans acquire language in only one way - by
understanding messages or by receiving "comprehensible input" ,
(Krashen, 1985a, p. 2)
The AcquisitionILearning Hypothesis: 'adults have two distinctive ways
of developing competences in second languages ... acquisition, that
is, by using language for real communication ... learning . .. "knowing about" language' (Krashen and Terrell, 1983, p. 26)
The Monitor Hypothesis: 'conscious leaming . . . can only be used as a
Monitor, or an editor' (Krashen and Terrell, 1983, p. 30)
The Natural Order Hypothesis: 'we acquire the mIes of language in a
predictable order' (Krashen, 1985a, p. 1)
The AtTective Filter Hypothesis: 'a mental block, caused by affective
factors. . . that prevents input from reaching the language acquisition
device' (Krashen, 1985a, p. 100)
Krashen's Five Hypotheses
3.2 KRASHEN'S EVIDENCE FOR THE INPUT
HYPOTHESIS
Let us look at the evidence in favour of the Input Hypothesis cited by
Krashen (1985a), supplemented when necessary from other sources.
(a) People speak to children acquiring their first language in special ways
Krashen (1985a) reviews some 1970s work on 'motherese' or 'caretaker
talk', that is to say, speech addressed to children acquiring their first
language. Motherese concentrates on the 'here and now' rather than on the
56
The Input Hypothesis Model
abstract and remote; tbis, coupled with its syntactic simplicity (Cross,
1977), gives it the qualities of comprehensible input. Motherese is not
'finely-tuned' to an exact i + 1 level one step ahead of the child, but
'roughly tuned' to the children's level, termed by Krashen elsewhere the
'net' - 'the speaker "casts a net" of structure around your current level,
your i' (Krashen and Terrell, 1983, p. 33).
(b) People speak to L2 learners in special ways
Some L2 learners encounter special language through the 'teacher talk'
addressed to students in the classroom. Krashen (1981) claims that this is
slower, is well-formed, has shorter sentences (Henzl, 1973), and has
simpler syntax (Gaies, 1977). The special variety of 'foreigner-talk' spoken
by natives to foreigners outside the classroom has similar characteristics;
foreigner-talk is simplified syntactically (Freed, 1980), and shows signs of
adaptation to the foreigner's level (Krashen, 1981, p. 131). These characteristics, wbile not the direct cause of acquisition, greatly improve the
comprehensibiIity of the input; 'the teacher, the more advanced second
language performer, and the native speaker in casual conversation, in
attempting to communicate with the second language acquirer, may
unconsciously make the "100 or maybe 1000 alterations in his speech" that
provide the acquirer with optimal input for language acquisition' (Krashen,
1981, p. 132).
(e) L21earners often go through an initial Silent Period
Krashen (1982) reviews case bistories that show that children often stay
silent in the L2 at first and start to talk at a later stage. Ervin-Tripp (1972),
for example, found that English-speaking children did not volunteer
speech in French-speaking schools for a prolonged period; according to
Dulay, et al. (1982, p. 23), Hakuta (1974) 'was unable to begin his study of
a Japanese child Uguisu until some five months after the subject had been
exposed to English because she produced almost no speech before that
time'. New overseas students at Essex University where I teach start every
academic year by complaining that their cbildren will not speak English
and end the year by complaining that their children speak English better
than they do. During this Silent Period in the L2, 'the child is building up
competence in the second language via listening, by understanding the
language around him' (Krashen, 1982, p. 27).
(d) The eomparative sueeess 0/ younger and older learners reflects provision
0/ comprehensible input
Krashen et al. (1982) analyse a large number of studies to come up with the
now widely held view that adults are better at short-term L2 learning,
cbildren at long-term L2 leaming. The reason is that 'older acquirers
progress more quickly in early stages because they obtain more compre-
Krashen's Evidence fOT the Input Hypothesis
57
hensible input, while younger acquirers do better in the long run because
of their lower affective filters' (Krashen, 1985a, p. 12). This is claimed to
be because older learners have greater experience of the world, can use the
LI to overcome communication problems in the L2 more easily, and are
better at conversational management.
(e) The more comprehensible input the greater the L2 projiciency
Some research results show that a larger amount of exposure to the L2
leads to proficiency. Krashen (1982) points out that students' length of
residence in the foreign country correlates with cloze test scores (Murakmi,
1980) and with dictation (Oller, Perkins and Murakmi, 1980); the length of
'time abroad' of the learners goes with the level of foreign language
proficiency (Carroll, 1967). Krashen (1989) also claims that reading skills
improve according to the amount of reading done, and that vocabulary
acquisition in the LI is helped by listening to stories. Sheer exposure
without comprehension is often useless to acquisition; watching television
in the L2 will only be useful if it is in some way comprehensible.
(f) Lack of comprehensible input delays language acquisition
Children of deaf or blind parents are sometimes delayed in language
development (Long, 1983) because of the lack of appropriate comprehensible input.
(g) Teaching methods work according to the extent that they use comprehensible input
Teaching methods that are comprehension-based, such as Total Physical
Response (TPR) (Asher, 1986) and the other listening-first methods presented in Winitz (1981), have, Krashen claims, been shown to have clear
advantages over traditional audiolingual methods. This is because they
make use of comprehensible input, not only in the spoken language but
also in the written; 'an approach that provides substantial quantities of
comprehensible input will do much better than any of the older approaches' (Krashen, 1982, p. 30).
(h) Immersion teaching is successful because it provides comprehensible
input
Immersion language teaching uses a second language as the medium of
instruction in the school, most famously in French immersion schools in
English-speaking Canada; 'it is the comprehensible input factor that is
responsible for the success of immersion' (Krashen, 1985a, p. 17). Krashen
finds a similar effect in 'sheltered' classes where non-native university
students are taught academic material in circumstances designed to make it
comprehensible to them.
58
The Input Hypothesis Model
(i) Bilingual programmes succeed to the extent that they provide comprehensible input
Bilingual teaching maintains the use of the mother-tongue alongside the
L2; one current example is the maintenance of the three languages of
Singapore spoken by its inhabitants (Chinese, Tamil, Bahasa Malaysia)
alongside English in the schools. The successful programmes are, according to Krashen, those that provide comprehensible input.
Linguistics and the Input Hypothesis Model
Krashen is proposing a general theory of second language acquisition that
attempts to answer the three questions posed in Chapter 1. He suggests
that knowledge of language in L2 users takes two forms: acquired and
leamt knowledge. Such knowledge is created by two separate processes:
'acquisition' using the natural built-in processes of the mind, and 'learning'
using conscious rational processes. The use of the L2 can involve a distinct
process of Monitoring which brings the speaker's leamt knowledge to bear
on the sentences produced by acquired knowledge.
In many ways Krashen's answers are within the general agenda set by
linguistics. The division into acquired and leamt knowledge reftects the
division of the mind into modular faculties; the language faculty is separate
from other faculties, such as the number faculty or the faculty of mathematics (Chomsky, 1980a). Linguists often assume that language itself is
leamt only through the language faculty, without utilising other faculties or
generalleaming abilities. The roles of a second language might be apprehended as conscious information through other faculties of the mind than
spontaneous language leaming as weU as through the usual language
faculty route, for example by a linguist working with a language he or she
does not speak. Krashen's distinction between acquired knowledge and
leamt knowledge is thus a variant on a familiar linguistics theme. Similarly
Krashen makes the Chomskyan Language Acquisition Device (LAD) a
core element in his model. The fact that acquisition relies on built-in
abilities of the mind reftects an assumption of the Chomskyan theory
already seen in preceding chapters in Selinker's concept of 'latent language
strocture' or Wode's universal strategies of the human mind.
The function of LAD is indeed to turn language input into a grammar of
the language. The Chomskyan LAD, however, works independently of the
features of the input. The point of this conceptualisation is to discover the
properties of LAD itself, not the properties of the input. But Krashen is
concemed with the properties of the input, rather than the processes of the
mind; he leaves the process of acquisition as mysterious as ever. To
Krashen, L2 acquisition is driven by the language environment rather than
by the mind and it is limited by the filter. The conditions for successful
acquisition matter more to him than the processes of acquisition. The
KTashen's Evidence fOT the Input Hypothesis
59
model does not interest itself in how comprehensible input is dealt with by
the mind. At best, certain features of language, such as grammatical
morphemes, seem to have a natural order of acquisition built-in to the
mind, which is not so much explained by the Input Hypothesis as taken for
granted.
Krashen claims that learners make sense of comprehensible input by
extra-linguistic means. Gregg (1984) uses Chomsky's argument for the
stimulus-free nature of language to show that there are no situational aids
which would actually help in acquiring, say, the third person singular" -s" .
McLaughlin (1987) points out that use of feedback is incompatible with the
claims for the Silent Period since those dealing with the learners would not
know the language level of their silent listeners weH enough to provide
adequate feedback. White (1987) accepts that some non-linguistic information is needed but questions 'Krashen's implication that this is the only
way we can make use of input which is beyond the current grammar'; she
argues that the passive construction could be learnt by lexical generalisation independent of contextual clues and that the 'triggering' of grammatical change, discussed in Chapter 9, is not driven by meaning. In many ways
Krashen is proposing a view of language acquisition similar to the interactionist LI model of Bruner (1983), which sees parents as providing carefuHy controHed language for their offspring within the context of sodal
interactions. Krashen's model differs in that the process relies on comprehension alone rather than on two-way conversations.
Krashen is also proposing something very different from the hypothesistesting model put forward in the 1960s, which was often linked to LAD, as
described in Chapter 1. In the Input Hypothesis model, the learner does
not test hypotheses but progresses along a pre-ordained sequence.
Hypothesis-testing necessitates trying out the rules and getting feedback;
hence it was abandoned by linguists after it became obvious that such
feedback rarely occurs in LI acquisition (Brown and Hanlon, 1970).
Comprehensible input, however, is effective regardless of whether the
learner ever speaks or gets feedback. In a way, Krashen is closer to the
more recent model of Universal Grammar (UG) , to be described in
Chapter 9, which also does not rely on feedback. But the Input Hypothesis
nevertheless relies on specific properties of the input where UG theory
uses characteristics to be found in any spoken language. Krashen makes no
suggestions about the internal structure of the Language Acquisition
Device: the black box is still as mysterious as ever. True as this may have
been of the LAD of the 196Os, the Universal Grammar equivalent of the
1980s made very detailed claims about the nature of the acquisition device.
The linguistic content of Krashen's work is based almost entirely on the
phrase structure analysis and grammatical morphemes discussed in
Chapter 2. Hence it is open to the same objection of lack of coverage; it
hardly begins to cover linguistic competence in terms of syntax, and seldom
60
The Input Hypothesis Model
mentions phonology or vocabulary. The analysis is based on treating rules
as items: you leam one rule after another, as you leam one vocabulary
item after another. Rules do not form a total system - a grammar - but are
separate items. Allianguage leaming, not just vocabulary, is then acquiring discrete items one at a time rather than acquiring an interlocking
grammatical competence. This seems to ignore the very nature of syntax:
whatever syntactic theory one adopts, the distinctive feature of syntax is
that it forms an overall system rather than a list of items. This point will
reoccur in the discussion of the Multidimensional Model in the next
chapter.1t is central to the independent-grammars assumption that rules of
the target language are not leamt additively but that each stage of interlanguage has a system of its own.
The Evidence for the Input Hypothesis
Let us examine the support for the Input Hypothesis that 'comprehensible
input (CI) is the essential environment al ingredient in language acquisition' (Krashen, 1989). In one sense comprehensible input is so blindingly
obvious that it has to be true; except for occasional off-beat language
teaching methods, it is unimaginable that the constant provision of incomprehensible speech actively promotes language leaming. In this sense
comprehensible input is simply an overall requirement within any theory of
SLA. The chief difficulty, pointed out by McLaughlin (1987) for example,
is the lack of definition of comprehensible input itself. In a way it is
circular: anything that leads to acquisition must be comprehensible input,
so comprehensible input is whatever leads to acquisition. The theory lacks
an explicit independent specification of the linguistic forms used in comprehensible input and of the types of situational help that make them comprehensible - its most central aspect.
Another difficulty is the implied relationship between listening and
speaking. In this model, acquisition depends on listening; it is not important whether the leamerspeaks or not. Gregg (1984) points to a lack of
evidence for the claim that speaking does not help acquisition, compared
to the oft-held belief that practice in speaking is indeed helpful to L2
acquisition; McLaughlin (1987) claims that access to one's own speech is an
important source of information in a hypothesis-testing view of language.
Swain (1985) argues that adequate progress in the L2 depends on interaction; listening is ineffective if it is not within a process of interactive
negotiation. The actual relationship between speaking and listening is
unknown. While speaking may be parasitic on listening, some theories
have assumed the opposite, such as the articulatory loop theory of memory
that relates intemal processing to covert articulation (Baddely, 1986);
Sinclair and EIlis (1992) indeed show within this framework that repeating
Welsh words aloud helps their acquisition compared to silent acquisition.
Krashen's Evidence for the Input Hypothesis
61
So me LI theorists insist on the initial separation of listening and speaking,
and see the child's problem essentially as learning how to relate them
(Clark and Hecht, 1983). Issidorides and Hulstijn (1992) show that, while
L2 learners of Dutch had problems producing Dutch word order, they had
little difficulty in comprehending them - the two aspects of language were
distinct.
In Cook (1991a) a distinction was made between the process of decoding
speech, in which the users utilise a code they already know to understand a
message, and the process of codebreaking speech, in which they try to work
out the code itself by understanding a message. Decoding speech has the
aim of discovering the message by using processes that are already known.
Codebreaking speech has the aim of discovering the processes themselves
from a message. Krashen's theory conflates decoding and codebreaking; to
Krashen decoding is codebreaking. The acquisition question and the use
question are collapsed into one by equating using with acquiring.
Let us come back to the more specific evidence for the Input Hypothesis
cited by Krashen. The evidence that there is special speech addressed to
children in first language acquisition [claim (a)] and that lack of comprehensible input delays first language acquisition [claim (f)] is not directly
relevant to SLA as it concerns LI learning; it needs L2 evidence to be
convincing.
Claim (b), that people speak to L2learners in special ways, is probably
true to some degree, even if the studies cited are not extensive. But the
existence of a special variety of language addressed to learners does not
show that it he/ps them to learn language; people have been speaking to
dogs in special ways for thousands of years, without any of them learning to
speak. There is no necessary cause-and-effect relationship between special
speech and effective learning - no indication that special speech helps
learners rather than being simply a conventional register. While Krashen
does not claim explicitly that simplified speech causes acquisition, the
weaker claim that caretaker speech helps by increasing comprehensibility
is unclear without more precise details. Gregg (1984), taking account of
work such as Newport (1976) with 'motherese', points out that it is not so
much that speech to learners is syntactically simpler as that it is different
from that addressed to native adults. White (1987) argues that simplified
input may in fact deprive the learner of information vital to acquisition, an
argument anticipated by language teachers who advocate the use of authentie speech in the classroom to fill gaps in the normal edited classroom
language. Above all , it is never certain that it is the comprehensibility of
the input that counts rather than its simplicity.
The initial Silent Period of L2 learners [claim (c)] is an intriguing
observation about L2 learning; Gibbons (1985), however, not only found
the evidence provided by Krashen unsatisfactory but also found an average
Silent Period of only 15.2 days for a sampie of 47 children ranging from 4:7
62
The Input Hypothesis Model
to 11:9 years learning English in Australia, with the Silent Period ranging
in length from 0 to 56 days. A non-speaking initial period does not show
the necessity of comprehensible input; it may, however, tell one a great
deal about the young child's embarrassment, isolation and sheer difficulty
in coping with a novel L2 environment. As Hakuta (1974) said of the
Japanese child Uguisu, 'very possibly it was a matter of confidence rather
than competence that she started talking' . Nor may this be unique to L2
learning situations; according to an experienced playgroup supervisor, if
you take the same period of 15 days, at least one in four English-speaking
children are silent in their LI when they start attending playgroup at
around two and a half years.
The differences between younger and older L2 learners [claim (d)] are
plausible, if still controversial. But they are often attributed to differences
in cognitive, social, or physical development; it is not clear that comprehensible input is the crucial factor. McLaughlin (1987) points out that the
here-and-nowness of speech addressed to younger children should mean
they actually get more comprehensible input than older learners, hence
they should do better in the short term rather than worse.
Claim (e), that the quantity of comprehensible input matters, is difficult
to sort out from claims about quantity of language exposure; no one denies
that, within limits, it helps to hear more language rather than less. Claim
(f) was covered with claim (a) above.
The evidence for the influence of comprehensible input on language
teaching - claims (g), (h), (i) - largely consists of generalisations about
complex teaching situations which involve so many factors relating to the
student, the teacher, and the situation that it is impossible to separate out
comprehensible input. The view that older methods ignored comprehensible input is surely incorrect; indeed, most methods of the past 30 years
insisted on the importance of making the meaning of sentences clear to
students, whether by the audiovisual method, the situational method, or
the communicative method. Perhaps only doctrinaire audiolingualism deemphasised comprehensible input in its structural drills, even if its advocates still asserted the priority of the passive oral skill of listening (Lado,
1964). Take the following description of the four elements in language
teaching:
First, there is a direct appeal to the ear, by which the language is
acquired. Secondly this appeal is made in circumstances where there is a
direct relation, ipso facto, established between the sound and the things
signified . . . Thirdly the same living appeal to the ear is continuously
and for a considerable length of time repeated. Fourthly the appeal is
made under circumstances which cannot fail strongly to excite the attention, and to engage the sympathies of the hearer. In these four points,
lies the whole plain mystery of Nature's method.
Evidence for the Other Hypotheses
63
Apart from the style, little betrays that this account of the virtues of
comprehensible input was not written by Krashen in 1985 but by J. S.
Blackie in 1845 (cited in Howatt, 1984). Comprehensible input has been
the core of many teaching methods, in spirit if not in name.
The advantages of immersion teaching [claim (i)] are currently seen as
less compelling than Krashen makes out; in some cases immersion seems to
lead to a fossilised classroom pidgin. Swain (1985) found many faults in
immersion learners after seven years of French, despite the wealth of
unarguably comprehensible input they had received. Evidence from immersion teaching is not clear-cut since the situation includes many factors
of situation and of learner other than comprehensible input. The evidence
for the superiority of listening-based methods [claim (h)] is striking, but
does not depend directly on comprehensible input; nor have comparisons
taken place between listening-based methods and so-called communicative
methods, or indeed mainstream EFL methods (Cook, 1986).
3.3 EVIDENCE FOR THE OTHER HYPOTHESES
So far the Input Hypothesis has been treated separately from the other
four hypotheses. Let us review the evidence for these briefly. Some such
distinction as the acquisition/learning hypothesis has been held by many
people. In the first half of this century, for instance Palmer (1926) proposed a distinction between the 'spontaneous' and 'studial' capaeities for
learning language. Undoubtedly this distinction conforms to the conseious
ideas of many L2 teachers and students. Research evidence for the separation of acquisition from learning is hard to find. Krashen (1985a) and
Dulay et al. (1982) eite none; Krashen (1982) and Krashen and Terrell
(1983) eite the use of error correction in L2 teaching as relying on a
separate process of 'Iearning'. The hypothesis is more an assumption than a
discovery.
Evidence for the Monitor Hypothesis is also held to be evidence for
acquisition/learning. Originally Krashen claimed Monitoring depended on
availability of time, but this claim now seems to be abandoned (Krashen,
1985a, p. 22) in the face of research by Hulstjin and Hulstjin (1983) that,
inter alia, showed that lack of time pressure was no more beneficial to
learners who knew the mIes explieitly than to those who did not, as
described in Chapter 10. Krashen emphasises the limitations of
Monitoring, and often claims that it only works for 'mies of thumb' that
make sense for the learner (Krashen, 1981). Krashen (1982) discusses case
histories which show Monitoring at work: a Chinese learner of English
known as P, for instance, produced spontaneous mistakes in speech that
she could correct according to conseious mies but made far fewer mistakes
64
The Input Hypothesis Model
in writing. No one would deny that some learners find consciously Iearnt
mIes unhelpful, nor that real-time language use cannot depend purelyon
consciously learnt linguistic knowledge, as those of us who used to spend
three hours on a paragraph of Latin composition will attest, nor that some
consciously acquired mIes cannot be converted into actual use - before
typing "receive" I still have to recite "i before e except after C or before g".
But such evidence does not prove that consciously learnt knowledge is
useIess, that all of it is availabIe only via the Monitoring process, or that, at
least for some Iearners, some of it does not convert into acquired knowledge. After all, many generations of students were taught English in Dutch
and Scandinavian universities by studying the works of such grammarians
as Jespersen, Zandvoort, and, more recently, Quirk. According to
Krashen, their academic knowIedge has had no effect on their ability to use
English in real life situations. Yet many of these students are among the
most ftuent L2 speakers of English. At Essex University, all modem
language undergraduates have to take a course in the linguistic description
of the language, because, the teachers claim, it has an important effect on
their language proficiency. The Monitor hypothesis and the claim for nointerface between acquired and Iearnt knowIedge seem to have insufficient
evidence of their own to outweigh the obvious counter-evidence.
But there are other hypotheses waiting in the wings. The Monitor
Hypothesis is closely linked to the Natural Order hypothesis. As support
for natural order, Krashen (1985a) cites the exampIes of grammatical
morphemes and negation seen in the last chapter, and others such as
"easy/eager to pIease" (Cook, 1973). Even if the sequences described in
the last chapter were accepted as valid, this would still amount to some
small proportion of what a full developmental scale would require, to be
equivaIent, say, to those described for first language acquisition in LARSP
(Crystal et al. 1976) or in the Bristol project (Wells, 1985). Hence the
actual sequence on which the i and i + 1 levels can be based is too emde to
support the links between natural order and comprehensible input for
more than a fraction of L2 Iearning at best. It is presumably tme that
acquiring certain aspects of language requires hearing examples of them in
circumstances that help the learner to make sense of them; but there is as
yet no clear L2 developmental scale that sets out the precise ladder on
which i and i + 1 form mngs, as McLaughlin (1987), for example, points
out.
Natural orders for grammatical morphemes are found in 'Monitor-free'
conditions; unnaturalorders are found when Monitoring is involved in
'pencil and paper "grammar" -type tests'. Monitoring causes an 'increase in
relative rank of two morphemes, regular past and the third person singular
marker' (Krashen, 1982, p. 101). Krashen does not explain why such a
natural order occurs or why these morphemes are particularly susceptibIe
to Monitoring; the hypothesis simply states it does occur. Whether or not
Models in SLA Research
65
the natural order is interfered with by Monitoring, whether or not this
shows a distinction between 'acquisition' or 'leaming', whether or not this
requires the notion of comprehensible input, all depends on a chain of
interlinked interpretations of research, never producing the bedrock on
which the others can rest.
Finally the Affective Filter hypothesis takes care of any variation that
has not been covered so far. The usual arguments presented by Krashen
(for example, Krashen, 1981) for an Affective Filter are: aptitude goes
with 'leaming' and attitude goes with 'acquisition', based on Gardner and
Lambert (1972); integrative motivation (the desire to take part in the
target culture) goes with proficiency in situations with rich intake available
(Gardner and Lambert, 1959); children have lower filters because of their
difference in conceptuallevel (Elkind, 1970). All these claims reinterpret
research carried out with other aims as evidence for a filter. For example,
although Gardner and Lambert (1959) showed integrative motivation was
important in high schoolleamers in Montreal, it is Krashen's inference that
this goes with an Affective Filter or with the type of language they were
given in the classroom. It is possible to accept all these factors as having
some effect on L2 leaming without accepting the existence of a filter or a
connection with comprehensible input. There is also a paradox in
Krashen's reliance on the Affective Filter to explain success or failure in
acquisition. The natural processes of LAD which are central to his model
are independent of the filter in the first language: all children leam their
first language. While it is possible to see attitudes as having a distinctive
effect on the L2 process, it is hard to see why they should affect 'acquisition', which supposedly underlies 'natural' leaming of both LI and L2,
rather than conscious 'leaming'.
3.4 MODELS IN SECOND LANGUAGE
ACQUISITION RESEARCH
As can be seen from the above, Krashen's ideas are both stimulating and
frustrating. They raise expectations by suggesting simple, plausible explanations for phenomena that many L2 users recognise; they provide immediate connections with the classroom. A simple set of propositions, each
of which makes sense about L2 leaming and which cumulatively seem to fit
together in a whole system, has great attractions. Part of the success of
Krashen's model has been its sheer scope and inclusiveness. Yet the
evidence for these ideas is elusive. Little direct evidence is provided for any
of the five hypotheses separately; they are linked through a chain of
inferences and through continual reinterpretation of pre-existing research
in terms of the model rather than through research designed specifically to
66
The Input Hypothesis Model
explore its claims. For this reason the model is like an axiom-based
mathematical or theological system that makes sense in its own terms but is
not verifiable in terms of the world outside, rather than a scientific theory
that is testable.
Since it first appeared, Krashen's work has been the subject of impassioned attacks, perhaps because of the frustrations involved in tracking
down the empirical basis for its claims. Intuitive as Krashen's theory may
be, it nevertheless attracts many people dealing with L2leaming, particularly teachers. Ellis (1990a, p. 57) talks of 'the lucidity, simplicity, and
explanatory power of Krashen's theory'. Lightbown (1984, p. 246) praises
its combination of 'a linguistic theory (through its "natural order" hypothesis), social psychological theory (through its "affective filter" hypothesis),
psychologicalleaming theory (through its acquisition-leaming hypothesis),
discourse analysis and sociolinguistic theory (through both the comprehensible input hypothesis and the "monitor" hypothesis )'. Krashen at least
attempted to make a large proposal which dealt with everything from
leamers' motivations to grammatical morphemes, from LAD to language
teaching. Perhaps its very scope made it too easy to find fault with some
aspect of it.
My own view is that Krashen's hypotheses do not, on closer inspection,
conform to the three linguistic questions. The knowledge question is
answered by postulating an opposition between acquired and leamt knowledge; but these are both knowledge of the L2 with no clear relationship to
the co-existing LI knowledge; L2 acquired knowledge is a paler version of
LI knowledge, weakened by the filter and its fall-back relationship to the
LI. The LI has a minor role in compensating for ignorance of the L2 rather
than being a coexisting element in the mind and a continual presence in
acquisition. The acquisition question is answered by describing the features
of the environment and the individual's mind that help or hinder acquisition rather than the acquisition processes themselves; the relationship to
the LI system is not specified apart from the notion of fall-back. Having
effectively cut the LI off from the L2, Krashen also cuts off acquired from
leamt knowledge, not allowing one to grow into the other during the
process of acquisition. The use question is answered by postulating a single
crucial process of production - Monitoring - rather than a full range. The
overall problem is the failure to recognise that the L2 user has two
languages in one mind. The Krashen theories treat L2 acquisition as an
impoverished version of LI acquisition rather than having the complexity
and richness of multi-competence.
The Input Hypothesis is perhaps the most extensive and controversial
model of second language acquisition. What is the status of such models in
SLA research? Informally a model is an attempt to relate several aspects of
some area in an overall framework; it ascends one level of explanation
from a single topic of research. One type of model can be considered a
Models in SLA Research
67
metaphor; the Greeks used models of the mind based on marionettes; later
models have been based on metaphors with hydraulics, mechanics, and
computers. The importance of such metaphors for understanding the world
is discussed by Lakoff and Johnson (1981). The black box LAD model with
its input/output relationship is of this metaphorical type, as is the thought
experiment of Schrodinger's Cat in physics. A metaphoric model is an aid
to understanding and no more. The appeal of Krashen's model is this
metaphorical mode; the arrows from acquired knowledge, the block
imposed by the Affective Filter, the black box of LAD, all help us to
understand L2 acquisition. A model in this sense eventually succeeds or
fails according to the lively research ideas it stimulates. But, as we have
seen, Krashen's ideas have led to bitter controversy rather than to the
development of a research paradigm or new research.
A model can altematively be understood as a construct in which each
element is empirically verifiable; every box, every arrow, has to be supported by precise evidence. To count as a model in this sense, the Input
Hypothesis would have to justify each of its elements in terms of hard
evidence. But no exact definition of comprehensible input is provided, no
clear way of separating acquisition from leaming, no real evidence for the
Monitor, no real explanation for the natural order, and so on. Though
couched as scientific 'hypotheses' and seeming to draw on a mass of
concrete research, the Input Hypothesis Model is too vague and too
unsupported to count as an empirically verifiable model of SLA that is
more than metaphoric. A contrast can be made with the Socio-educational
model of Gardner (1985), which also lays out the relationship between
different aspects of L2 acquisition in terms of motivation, aptitude, and the
like. But each of Gardner's boxes is supported by tests specially designed
to provide appropriate evidence and each of the connecting arrows has
been tested mathematically for its strength. Gardner's model lies outside
the scope of this book as it is psychologically rather than linguistically
based; it is described briefly in Cook (1991a). But, whether one agrees with
it or not, it sets a standard for model creation in that all its claims depend
on actual evidence. The problem with the Input Hypothesis is how you
could show it was wrong. In the comic science fiction novel The Twilight 0/
the Vilp (Ableman, 1969), Professor Pidge claims that a cardboard box is a
perfect model of the human mind with the origin of language being the
words "Sundazil Polishing Powder" stencilled on the side. A model that
has no way of being proved wrong is as scientific as Professor Pidge's.
The other general question about models in SLA research concems their
relationship with other disciplines. It is perfect1y proper for SLA research
to postulate theories of its own to explain its own area. It is also proper for
it to offer its discoveries to other disciplines to help them solve their
problems. So SLA research may produce information of interest to first
language researchers, to cognitive psychologists, to theoreticallinguists, or
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The Input Hypothesis Model
to language teachers. It is also appropriate for SLA research to take
insights and methods from these disciplines when they are useful to it;
much of the SLA research discussed so far has been indebted to the first
language acquisition research of the 1960s in one way or another. But SLA
research has to be cautious when it starts making claims that go outside its
territory. Krashen's claims that there are two forms of language knowledge
make assertions about areas that belong to the allied disciplines of philosophy, psychology and linguistics. The model assigns consciousness the
partieular role of Monitor; again the value of consciousness in human life is
something which extends across philosophy to psychology and to linguisties. Acquiring a language and using a language are considered the same
activity of utilising comprehensible input, a redraft of the core acquisition
and use questions of linguistics. If an SLA model is to make claims outside
its remit, they must at least be reconcilable with current models used in
these areas. SLA research cannot redesign the whole of the human mind to
fit its own convenience, ignoring all the disciplines that also deal with the
mind.
The point of a model then is its help with understanding a complex area
and with opening ways forward. In Gardner's words: 'A true test of any
theoretical formulation is not only its ability to explain and account for
phenomena which have been demonstrated but also its ability to provide
suggestions for further investigations, to raise new questions, to promote
further developments and open new horizons' (Gardner, 1985, p. 167).
SLA models are useful in so far as they develop and increase our understanding of L2 leaming; they hinder if they are not stated precisely enough
to be be testable and if they are regarded as final solutions to be defended
to the bitter end rather than as working hypotheses to be changed or
dropped when necessary. The main thrust of this chapter has been that,
while Krashen proposed a theory that was extremely stimulating and that
provided the first attempt at wider explanation of second language acquisition, it did not have sufficient substance on which to build newer and
better theories.